Contact arrangement for an electrical switching device especially for a contactor

Abstract

A contact arrangement provided for an electrical switching device, particularly for a contactor or protective relay, includes a stationary contact element and a movable contact element. The stationary contact element essentially consists of an elongated current lead-in member, at the end region of which there is affixed a contact member. At this contact member there is adjacently arranged an arc guiding element which is supported at the elongated current lead-in member, but is electrically conductively connected to the current lead-in member solely at an end portion thereof. At the surface or side facing away from the elongated current lead-in member, the arc guiding element is provided on an end surface area confronting the contact member with a projection which is formed of ferromagnetic material and symmetrically arranged in the center of the arc guiding element. The shortest distance between the contact member and the projection is, at most, one half of the extent of the projection in the lengthwise direction of the arc guiding element. The contactor equipped with this contact arrangement can interrupt relatively high short-circuit currents and possesses a sufficiently long service life.

What I claim is: 
     
       1. A contact arrangement for an electrical switching device, especially for a contactor, comprising: a stationary contact element;   a movable contact element;   said stationary contact element comprising an elongated current lead-in member having an end portion and a predetermined lengthwise direction;   a first contact member provided on said end portion of said elongated current lead-in member;   an arc guiding element adjacently arranged on said first contact member and defining on said first contact member an adjoining location;   said arc guiding element extending at least in the area of said adjoining location in a direction substantially parallel to said predetermined lengthwise direction of said elongated current lead-in member and being electrically conductively connected with said elongated current lead-in member solely in close proximity to said adjoining location;   said movable contact element comprising a current-carrying piece;   a second contact member provided on said current-carrying connecting piece;   said current-carrying connecting piece being situated opposite said elongated current lead-in member and said arc guiding element;   said arc guiding element having an end region confronting said first contact member provided at said end portion of said elongated current lead-in member and a side facing away from said elongated current lead-in member;   said end region of said arc guiding element containing a center;   a projection formed of a ferromagnetic material and symmetrically arranged relative to said center of said end region and on said side of said arc guiding element facing away from said elongated current lead-in member;   said arc guiding element having a predetermined lengthwise direction;   said projection having a predetermined extent in said predetermined lengthwise direction of said arc guiding element; and   a shortest distance between said contact member on said elongated current lead-in member and said projection being at most one half of said predetermined extent of said projection in said predetermined lengthwise direction of said arc guiding element.   
     
     
       2. The contact arrangement as defined in claim 1, wherein: said projection possesses the shape of a spherical segment.   
     
     
       3. The contact arrangement as defined in claim 1, wherein: said projection possesses the shape of a cylinder.   
     
     
       4. The contact arrangement as defined in claim 3, wherein: said cylinder-shaped projection comprises a projecting end; and   said projecting end being rounded off.   
     
     
       5. The contact arrangement as defined in claim 1, wherein: said arc guiding element possesses a predetermined width; and   the width of said projection being in the range of 0.2 to 0.6 times said predetermined width of said arc guiding element.   
     
     
       6. The contact arrangement as defined in claim 1, wherein: said first contact member of said stationary contact element and said second contact member of said movable contact element define a predetermined contact break distance; and   the height of said projection being in a range of 0.2 to 0.8 times said predetermined contact break distance.   
     
     
       7. The contact arrangement as defined in claim 1, wherein: said projection is mounted at said arc guiding element.   
     
     
       8. The contact arrangement as defined in claim 7, wherein: said projection is provided with a stem and comprises a mushroom form; and   said stem being inserted into said arc guiding element.   
     
     
       9. The contact arrangement as defined in claim 1, wherein: said arc guiding element is formed of a ferromagnetic material; and   said projection being structured in one piece with said arc guiding element formed of a ferromagnetic material.   
     
     
       10. The contact arrangement as defined in claim 1, wherein: said side of said arc guiding element facing away from said elongated current lead-in member constitutes a surface;   said movable contact element having an open position;   said movable contact element comprising an edge;   said edge of said movable contact element in said open position confronting said arc guiding element and defining a distance therebetween; and   said distance between said surface and said edge continuously increasing, starting from said projection, in said predetermined lengthwise direction of said arc guiding element.